This invention relates in general to photography. More particularly, it relates to a photographic fixing composition, and to a method of processing color photographic silver halide elements using that composition.
The basic image-forming process of color silver halide photography comprises the exposure of a silver halide color photographic recording material to actinic radiation (such as light) and the manifestation of a useful image by wet chemical processing of the material. The fundamental steps of this wet processing include color development to reduce silver halide to silver and to produce dye images in exposed areas of the material. During or after bleaching to oxidize metallic silver to silver(I), the silver ion is generally removed by dissolving it in a silver solvent, commonly known as a fixing agent.
In some photochemical processes, bleaching and fixing are combined in a bleach-fixing step using a composition that includes both a bleaching agent to oxidize metallic silver and a fixing agent to dissolve the remaining silver ion.
A wide variety of fixing agents and silver solvents are known, as described for example in U.S. Pat. No. 5,633,124 (Schmittou et al.) and publications noted therein. Thiosulfate salts are generally preferred as fixing agents because they are inexpensive, highly water soluble, non-toxic, non-odorous, and stable over a wide pH range. Thus, fixing is usually accomplished using a thiosulfate fixing agent that diffuses into the element, and forms silver thiosulfate complex that diffuses out of the element. In large photofinishing labs, the elements are usually immersed in a fixing solution for from 4 to 6 minutes. In small minilabs, the fixing time is shorter, that is from 90 to 120 seconds.
Fixing compositions are generally buffered to a pH of from about 4 to about 8 to achieve maximum silver xe2x80x9cfixingxe2x80x9d using common buffering agents such as acetic acid, succinic acid, or malic acid. They also usually include sulfite ions to serve as a silver halide solvent, to help control pH, and to act as a preservative. While such fixing compositions are effective for their intended purpose, they may have objectionable odor and keeping problems as decomposition reactions can form sulfur.
Thus, there is a need for a highly effective photographic fixing composition that has reduced odor and improved keeping stability.
This invention provides a photographic fixing composition that has a pH of from about 4 to about 12 when in aqueous form, and comprises:
at least 0.05 mol/l of a thiosulfate fixing agent,
at least 0.01 mol/l of sulfite ions, and
at least 0.025 mol/l of a phthalic acid or a salt thereof.
This invention also provides a method for providing a color photographic image comprising contacting a color developed color photographic silver halide material with the photographic fixing composition described above.
In another embodiment, a method for providing a color photographic image comprises:
A) color developing an imagewise exposed color photographic silver halide material in a predetermined volume of an aqueous color developing composition in a processing chamber, and
B) without removing the predetermined volume of the aqueous color developing composition or the color photographic silver halide material from the processing chamber, adding a predetermined volume of the photographic fixing composition described above to the processing chamber to provide a combined aqueous color development/fixing composition, and fixing the color photographic silver halide material.
Further embodiments include an additional step of:
C) without removing the combined aqueous color development/fixing composition or the color photographic silver halide material from the processing chamber, adding a predetermined volume of a photographic bleaching composition to the processing chamber to provide a combined aqueous color development/fixing/bleaching composition, and bleaching the color photographic silver halide material.
The photographic fixing composition of this invention has been shown to have improved keeping stability and reduced odor without diminishing its photographic processing properties. These advantages are achieved by using a phthalic acid or a salt thereof in the fixing composition.
The photographic fixing compositions of this invention generally have a pH of from about 4 to about 12 when in aqueous form. Preferably, the pH is from about 4 to about 8, and more preferably, it is from about 4.5 to about 7.
The photographic fixing composition can be packaged and transported as a dry or liquid formulation, working strength solution, or as a single-part concentrated composition. It can be used as a replenisher as well as the initial tank working solution. Preferably, the photographic fixing composition is provided in aqueous form.
It should be understood that the photographic fixing compositions of this invention are intended for rapid and efficient removal of silver(I) from color photographic elements, either before, during or after bleaching, or any combination of these. Preferably, however, the fixing compositions have fixing activity only (no purposely added bleaching agents), and the only bleaching agents that may be present in the fixing composition are those carried over from a preceding bleaching solution by the photographic element being processed.
The first essential component in the photographic fixing composition comprises one or more thiosulfate fixing agents. The thiosulfate can be any of sodium thiosulfate, potassium thiosulfate, ammonium thiosulfate, lithium thiosulfate, calcium thiosulfate, or magnesium thiosulfate, or mixtures thereof such that a desired concentration of thiosulfate ion is provided. Preferably, ammonium thiosulfate or sodium thiosulfate (or a mixture thereof) is used. For rapid fixing, ammonium thiosulfate is preferably used.
Optionally, one or more thiocyanate fixing agents can also be present as a fixing agent especially for more rapid silver removal. If present, it can be provided as sodium thiocyanate, potassium thiocyanate or ammonium thiocyanate, or mixtures thereof. Preferably ammonium or sodium thiocyanate (or mixtures thereof) is used. The thiosulfates and thiocyanates can be obtained from a number of commercial sources or prepared using conventional starting materials and synthetic procedures.
A second essential component of the photographic fixing composition is a source (or mixture of sources) of sulfite ions. Useful salts that provide sulfite ions include but are not limited to sodium sulfite, potassium sulfite, ammonium sulfite, sodium bisulfite, sodium metabisulfite, potassium metabisulfite, and mixtures of such salts such that the desired sulfite concentration is obtained.
The third essential component of the photographic fixing composition is a phthalic acid or a salt thereof. By xe2x80x9ca phthalic acidxe2x80x9d, we mean to include substituted phthalic acids. Preferred salts of phthalic acid include hydrogen phthalates such as sodium hydrogen phtbalate, potassium hydrogen phthalate, ammonium hydrogen phthalate, lithium hydrogen phthalate, sodium phthalate, and potassium phthalate. Potassium hydrogen phthalate and sodium hydrogen phthalate are preferred. Mixtures of two or more of these compounds can also be used.
The concentrations (general and preferred) of the three essential components of the photographic fixing composition of this invention are listed in TABLE I below wherein all of the ranges of concentrations are considered to be approximate (that is xe2x80x9caboutxe2x80x9d).
If a thiocyanate fixing agent is also present in the photographic fixing composition, it is generally present in an amount of from about 0.05 to about 5 mo/l.
Optional addenda that can be present in the photographic fixing composition if desired are materials that do not materially affect its photographic fixing function. Such materials include, but are not limited to, biocides, alkyl or arylsulfinic acids or their salts, halides (such as bromide ions, chloride ions, or iodide ions), photographic hardeners, conventional buffering agents (such as acetic acid or succinic acid), metal ion sequestering agents (such as polycarboxylic acids, polyaminopolycarboxylic acids, and polyphosphonic acids), fixing accelerators, and other materials readily apparent to one skilled in the photographic art. These and other optional materials can be present in conventional amounts [for example as described in U.S. Pat. No. 5,633,124 (noted above].
The essential and optional components of the photographic fixing compositions of this invention can be mixed together in any suitable order as would be known in the art, and stored for a time or used immediately as liquid or solid formulations. They can be formulated in aqueous concentrates such that dilution up to 10 times is required before or during use. Alternatively, they can be formulated as solid compositions (tablets, pellets, powders or granules) and added to a processing tank with appropriate amounts of water for use.
During photographic processing, conventional procedures can be used for replenishment of the various processing solutions, including the photographic fixing solution. Preferably, the rate of fixing solution replenishment is not more than 3000 ml/m2, and preferably from about 250 to about 1500 ml/m2 of processed photographic material. The processing equipment can be any suitable processor having one or more processing tanks or vessels, including minilab processors and larger scale processors. The fixing step can be carried out in one or more tanks or stages arranged in concurrent or countercurrent flow.
The present invention can be used advantageously with any of the known methods of applying photographic fixing compositions to photographic materials. These methods include, but are not limited to, immersing the material into an aqueous fixing composition (with or without agitation or circulation), bringing the material into contact with a web or drum surface that is wet with the fixing composition, laminating the material with a cover sheet or web in such a way that the fixing composition is brought into contact with the material, or applying the fixing composition to the material by high velocity jet or spray.
The fixing step can be generally carried out at a temperature of from about 20 to about 65xc2x0 C. (preferably from about 30 to about 60xc2x0 C.). The time of processing during this fixing step is generally up to 360 seconds and preferably at least 10 and up to 240 seconds (more preferably from about 10 to about 120 seconds).
The other processing steps needed to provide color images can be similarly rapid or conventional in time and conditions. Preferably the other processing steps, such as color development, bleaching, and/or stabilizing (or rinsing), are likewise shorter than conventional times. For example, color development can be carried out for from about 12 to about 360 seconds, bleaching for from about 12 seconds to about 8 minutes, and stabilizing (or rinsing) for from about 15 to about 240 seconds in various processing protocols. The fixing step can be carried out more than once in some processing methods. The processing methods can have any of a wide number of arrangements of steps, as described for example in U.S. Pat. No. 5,633,124 (noted above) that is incorporated herein by reference.
In rapid processing methods, the total processing time for color negative films, can be up to 360 seconds (preferably from about 60 to about 250 seconds), and the total processing time for color papers can be up to 100 seconds (preferably from about 40 to about 100 seconds).
The present invention can therefore be used to process silver halide materials of various types including color papers (for example using Process RA-4), color motion picture films and prints (for example using Process ECP, Process ECN and Process VNF-1), and color negative films (for example using Process C-41) or color reversal films (for example using Process E-6). The various processing sequences, conditions and solutions for these processing methods are well known in the art.
Preferably, the photographic fixing composition of this invention is used in a novel rapid processing protocol that is identified herein as a xe2x80x9cmerged solutionxe2x80x9d processing method. This method generally includes, in order, color development and fixing, and optionally bleaching.
For example, a color photographic image can be provided (especially in color negative films) by the following steps:
A) color developing an imagewise exposed color photographic silver halide material in a predetermined volume of an aqueous color developing composition in a processing chamber, and
B) without removing the predetermined volume of the aqueous color developing composition or the color photographic silver halide material from the processing chamber, adding a predetermined volume of the photographic fixing composition of this invention to processing chamber to provide a combined aqueous color development/fixing composition, and fixing the color photographic silver halide material.
Preferably, the xe2x80x9cmerged solutionxe2x80x9d processing method further includes the step of:
C) without removing the combined aqueous color development/fixing composition or the color photographic silver halide material from the processing chamber, adding a predetermined volume of a photographic bleaching composition to the processing chamber to provide a combined aqueous color development/fixing composition to provide a combined aqueous color development/fixing/bleaching composition, and bleaching the color photographic silver halide material.
Alternatively, after step B, the color photographic silver halide material or combined color development/fixing composition can be removed from the processing chamber and further processed with one or more separate processing compositions, such as a photographic bleaching composition, in the same or different processing chamber.
There can be additional processing steps between steps A and B (such as use of a washing or xe2x80x9cstopxe2x80x9d solution), or between steps B and C (such as use of a washing solution), or after step C (such as use of a washing, rinsing, or stabilizing solution). It may be particularly useful to include an acidic xe2x80x9cstopxe2x80x9d solution between steps A and B. Solutions added between steps A and B, or between B and C, will necessarily be included in the final solutions that can be discarded or regenerated in any suitable manner. Alternatively, solutions added after step C can also be included in the final solutions of the method. In other words, steps carried out after step C can be conventional processing steps or additional xe2x80x9cmerged solutionxe2x80x9d processing steps.
The volumes of the various processing compositions used in the methods of this invention will vary depending upon the type of color photographic material being processed and the particular processing protocol used (for example, from large tank volumes to xe2x80x9cminilabxe2x80x9d volumes).
When the xe2x80x9cmerged solutionxe2x80x9d process is used, for example, to process color negative film, the predetermined volume of color developing composition introduced into the processing chamber is generally from about 50 to 2850 ml/m2 and preferably from about 140 to about 1170 ml/m2, of surface area of processed color photographic silver halide material. The predetermined volume of fixing composition introduced into the processing chamber may be sufficient to provide an additional volume of from about 6 to about 2000 ml/m2 and preferably from about 20 to about 800 ml/m2, per surface area of processed color photographic silver halide material Intermediate (for example washes, or xe2x80x9cstopxe2x80x9d solutions) or additional processing compositions (such as a bleaching composition) may be introduced into the processing chamber to each provide an additional volume of from about 6 to about 2000 ml/m2 and preferably from about 20 to about 800 ml/m2, of surface area of processed color photographic silver halide material.
For processing color papers using the xe2x80x9cmerged solutionxe2x80x9d processing method, the predetermined volumes of color developing composition introduced into the processing chamber may be generally from about 30 to about 400 ml/m2 and preferably from about 40 to about 150 ml/m2 The fixing composition can be then introduced into the processing chamber sufficient to provide an additional volume of from about 1 to about 220 ml/m2 and preferably from about 10 to about 100 ml/m2.
Thus, the volumes of processing solutions can be large like those used in the more conventional Process C-41 processing methods, or small like those generally used in xe2x80x9cminilabsxe2x80x9d or xe2x80x9cSMxe2x80x9d processors.
The one or more processing steps in this xe2x80x9cmerged solutionxe2x80x9d processing method can be carried out at the same or different temperatures generally within the range of from about 20 to about 65xc2x0 C., and preferably at from about 30 to about 60xc2x0 C.
In the xe2x80x9cmerged solutionxe2x80x9d processing method, step A is generally carried out for at least 15 seconds, and preferably for at least 25 seconds, and up to 195 seconds for color negative films and color papers, and up to 360 seconds for color reversal films.
If a xe2x80x9cstopxe2x80x9d solution is used between steps A and B, this intermediate step is generally carried out for at least 5 seconds, preferably 10 seconds, and up to 60 seconds.
Step B is then carried out for at least 5 seconds, and preferably for at least 10 seconds, and up to 120 seconds for color negative films, up to 90 seconds for color papers, and up to 300 seconds for color reversal films.
After at least 5 seconds of fixing in Step B, the photographic bleaching composition can be added to the combine aqueous color development/fixing composition. Fixing will continue for a time simultaneously with bleaching. Step C can then be carried out for at least 10 seconds, and preferably for at least 25 seconds, and up to 240 seconds for color negative films and color papers and up to 360 seconds for color reversal films.
In the xe2x80x9cmerged solutionxe2x80x9d processing method, the essential steps are carried out in the same processing chamber that can be of suitable size and shape to accommodate the processed materials and the various volumes of processing compositions that are added together throughout the various processing steps. The larger the volume of fluids added and the more steps used, the larger the processing chamber will likely be. In preferred embodiments, the volumes of each processing composition is small so that the total volume of the combined solutions at the end of the processing method is easily discarded. In such instances, the processing method can be considered a xe2x80x9csingle-usexe2x80x9d processing method.
One suitable processing apparatus that can be used to carry out the xe2x80x9cmerged solutionxe2x80x9d processing method is described in more detail in copending and commonly assigned U.S. Ser. No. 09/920,495 (filed Aug. 1, 2001 by Twist et al.).
Thus, in one embodiment of the xe2x80x9cmerged solutionxe2x80x9d processing method of this invention, a suitable processing chamber is loaded with an imagewise exposed color photographic material to be processed, and a metered (predetermined) amount of color developing composition is introduced into the chamber. Color development is then allowed to proceed for a suitable time. Without removing the color photographic material or color developing composition from the processing chamber, a metered (predetermined) amount of the fixing composition of this invention in then introduced into the processing chamber to provide a combined color developing/fixing composition. Fixing is then carried out for a suitable time. An intermediate xe2x80x9cstopxe2x80x9d solution can be introduced prior to addition of the fixing composition.
Without removing the color photographic material or the combined color developing/fixing composition, a metered (predetermined) amount of a bleaching composition is added to the processing chamber to provide a combined color developing/fixing/bleaching composition. Bleaching is then carried out for a suitable time. Additional processing steps (such as washing, rinsing, or stabilizing) can be carried out if desired in the same or different processing chamber and with or without removal of the combined color developing/fixing/bleaching composition.
In each of these processing steps, each solution is spread uniformly over the entire surface of the color photographic material to provide uniform processing. Each processing step is preferably carried out in a high agitation, batch processor that is used to process one color photographic material at a time with small volumes.
Further details of these processing embodiments are provided in copending and commonly assigned U.S. Ser. No. 10/012,673 filed on even date herewith by Twist and entitled xe2x80x9cProcessing Photographic Materialxe2x80x9d.
The emulsions and other components, and structure of color photographic materials used in this invention and the various procedures for manufacturing them are well known and described in considerable publications, including, for example, Research Disclosure, publication 38957, pages 592-639 (September 1996), and Research Disclosure, Volume 370, February 1995, and hundreds of references noted therein. Research Disclosure is a publication of Kenneth Mason Publications Ltd., Dudley House, 12 North Street, Emsworth, Hampshire PO10 7DQ England (also available from Emsworth Design Inc., New York, N.Y. 10011). This reference will be referred to hereinafter as xe2x80x9cResearch Disclosurexe2x80x9d. More details about such materials are provided herein below. In particular, the invention can be practiced with photographic films containing any of many varied types of silver halide crystal morphology, sensitizers, color couplers, and addenda known in the art, as described in the noted Research Disclosure publication and the many publications noted therein. The films can have one or more layers, at least one of which is a silver halide emulsion layer that is sensitive to electromagnetic radiation, disposed on a suitable film support (typically a polymeric material).
The processed color negative films may have a magnetic recording layer, or stripe, on the support opposite the silver halide emulsion layer(s). Formulations for preparing magnetic recording layers are also well known in the art, as described for example, in Research Disclosure, publication 34390, November, 1992, U.S. Pat. No. 5,395,743 (Brick et al.), U.S. Pat. No. 5,397,826 (Wexler), and Japanese Kokai 6-289559 (published Oct. 18, 1994), all incorporated herein by reference. The magnetic recording layers generally include a dispersion of ferromagnetic particles in a suitable binder. While the magnetic recording layer can cover only a portion of the surface of the support, generally it covers nearly the entire surface, and can be applied using conventional procedures including coating, printing, bonding, or laminating.
Various supports can be used for such color negative films processed according to this invention including the conventional acetates, cellulose esters, polyamides, polyesters, polystyrenes and others known in the art. Polyesters such as poly(ethylene terephthalate), poly(ethylene naphthalate), poly-1,4-cyclohexanedimethylene terephthalate, polyethylene 1,2-diphenoxyethane4,4xe2x80x2-dicarboxylate and poly(butylene terephthalate) are preferred. These materials can be subbed or unsubbed and coated with various antihalation, antistatic, or other non-imaging layers as is known in the art. Particularly useful antistatic layers on the backside of the materials include vanadium pentoxide in a suitable binder.
Representative photographic materials that can be processed to advantage using the present invention include, but are not limited to, KODAK ROYAL GOLD Color Films (especially the 1000 speed color film), KODAK GOLD MAX Color Films, KODAK ADVANTIX Color Films, KODAK VERICOLOR III Color Films, KONICA VX400 Color Film, KONICA Super SR400 Color Film, KONICA CENTURIA Color Negative Films, FUJI SUPERIA and NEXIA Color Films, and LUCKY Color Films. Other elements that could be used in the practice of this invention would be readily apparent to one skilled in the art.
Reagents for color development compositions are well known, and described, for example, in Research Disclosure (noted above), sections XVIII and XIX, and the many references described therein. Thus, besides a color developing agent (such as a p-aminophenol or p-phenylenediamine), the color developers can include one or more buffers, antioxidants (or preservatives, such as sulfo-,carboxy, and hydroxy-substituted mono- and dialkylhydroxylamines), antifoggants, fragrances, solubilizing agents, brighteners, halides, sequestering agents, and other conventional addenda. Representative teaching about color developing compositions can also be found in U.S. Pat. No. 4,170,478 (Case et al.), U.S. Pat. No. 4,264,716 (Vincent et al.), U.S. Pat. No. 4,482,626 (Twist et al.), U.S. Pat. No. 4,892,804 (Vincent et al.), U.S. Pat. No. 5,491,050 (Brust et al.), U.S. Pat. No. 5,709,982 (Marrese et al.), U.S. Pat. No. 6,037,111 (Haye et al.), U.S. Pat. No. 6,017,687 (Darmon et al.), U.S. Pat. No. 6,077,651 (Darmon et al.), U.S. Ser. No. 09/706,463 (filed Nov. 3, 2000 by Haye et al.), and U.S. Ser. No. 09/706,474 (filed Nov. 3, 2000 by Arcus et al.), all incorporated herein by reference.
A preferred photographic color developing composition has a pH of from about 9.5 to about 13 and comprises 4-(N-ethyl-N-xcex2-hydroxyethylamino)-2-methylaniline sulfate (KODAK CD-4 Color Developing Agent), bromide ions, sulfite ions, and a carbonate buffer.
Photographic bleaching compositions are also well known, as described for example, in Research Disclosure (noted above), section XX and the many references noted therein. Common bleaching agents for such compositions include, but are not limited to, ferric salts or ferric binary or ternary complexes of aminopolycarboxylic acids of many various structures including but not limited to ethylenediaminetetraacetic acid, 1,3-propylenediaminetetraacetic acid, iminodiacetic acid, methyliminodiacetic acid, ethylenediaminedisuccinic acid (either the S,S isomer alone or a racemic mixture of isomers), ethylenediamine monosuccinic acid, and others as described for example in U.S. Pat. No. 5,334,491 (Foster et al.), U.S. Pat. No. 5,582,958 (Buchanan et al.), U.S. Pat. No. 5,585,226 (Strickland et al.), U.S. Pat. No. 5,652,085 (Wilson et al.), U.S. Pat. No. 5,670,305 (Gordon et al.), and U.S. Pat. No. 5,693,456 (Foster et al.), all incorporated herein by reference.
A particularly useful photographic bleaching composition has a pH of from about 3 to about 8 and comprises 1,3-propylenediaminetetraacetic acid (or salt thereof), ferric nitrate, and succinic acid.
Stabilizing or rinsing compositions can include one or more surfactants, and in the case of stabilizing compositions, a dye stabilizing compound such as a formaldehyde precursor, hexamethylenetetraamine or various other aldehydes such as m-hydroxybenzaldehyde. Useful stabilizing or rinsing compositions are described in U.S. Pat. No. 4,859,574 (Gonnel), U.S. Pat. No. 4,923,782 (Schwartz), U.S. Pat. No. 4,927,746 (Schwartz), U.S. Pat. No. 5,278,033 (Hagiwara et al.), U.S. Pat. No. 5,441,852 (Hagiwara et al.), U.S. Pat. No. 5,529,890 (McGuckin et al.), U.S. Pat. No. 5,534,396 (McGuckin et al.), U.S. Pat. No. 5,578,432 (McGuckin et al.), U.S. Pat. No. 5,645,980 (McGuckin et al.), and U.S. Pat. No. 5,716,765 (McGuckin et al.), all incorporated herein by reference.
The photographic fixing composition of this invention can be provided in any suitable container, and can also be included in a processing kit with one or more other processing compositions in suitable containers.